Tsunami inundation and sediment transport in a sediment-limited embayment on American Samoa

Apotsos, Alex; Gelfenbaum, Guy; Jaffe, Bruce E.; Watt, Steve; Peck, Brian; Buckley, Mark; Stevens, Andrew W.

doi:10.1016/j.earscirev.2010.11.001

Cited by 57 publications

(49 citation statements)

References 26 publications

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“…This conclusion is in agreement with what was observed during several modern post-tsunami field surveys Sato et al 1995;Shi et al 1995;Richmond et al 2012): the main source of tsunami deposits came from beach areas or local sand. Similar conclusions were also mentioned by Apotsos et al (2011b) who simulated tsunami inundation and sediment transport in a sediment-limited embayment on American Samoa; their simulations showed that the amount of sediment available for transport could affect the onshore deposition thickness by more than 50 % by.…”

Section: Influence Of Sediment Supplysupporting

confidence: 73%

Numerical simulation of erosion and deposition at the Thailand Khao Lak coast during the 2004 Indian Ocean tsunami

Huang

Qiu

2014

Nat Hazards

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A case study was conducted for the Thailand Khao Lak coast using a forward numerical model to understand uncertainties associated with interpreting tsunami deposits and relating them to their tsunami sources. We examined possible effects of the characteristics of tsunami source, multiple waves, sediment supply and local land usages. Numerical results showed that tsunami-deposit extent and thickness could be indicative of the slip value in the source earthquake near the surveyed coastal locations, provided that the sediment supply is unlimited and all the deposits are well preserved. Deposit thickness was found to be largely controlled by the local topography and could be easily modified by backwash flows or subsequent tsunami flows. Between deposit extent and deposit thickness, using deposit extent to interpret the characteristics of a tsunami source is preferable. The changing of land usages between two tsunami events could be another important factor that can significantly alter deposit thickness. There is a need to develop inversion models based on tsunami heights and/or run-up data for studying paleotsunamis.

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Section: Influence Of Sediment Supplysupporting

confidence: 73%

Numerical simulation of erosion and deposition at the Thailand Khao Lak coast during the 2004 Indian Ocean tsunami

Huang

Qiu

2014

Nat Hazards

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“…For example, on American Samoa, erodable, sandy sediment is often only available along narrow beaches (∼20 m wide). This limited supply of sediment has been suggested as the reason for the thin, patchy nature of the tsunami deposit observed following the 29 September 2009 South Pacific tsunami [ Apotsos et al , 2010b]. However, while variations in these parameters affect the relative magnitude of the predicted processes and details of the onshore deposit, the general conclusions drawn here are not unique to the values chosen [see Apotsos et al , 2009].…”

Section: Discussionmentioning

confidence: 91%

Process-based modeling of tsunami inundation and sediment transport

2011

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[1] The infrequent and unpredictable nature of tsunamis precludes the use of field experiments to measure the hydrodynamic and sediment transport processes that occur. Instead, these processes are often approximated from laboratory, numerical, and theoretical studies or inferred from observations of the resultant sediment deposits. Here Delft3D, a three-dimensional numerical model, is used to simulate the inundation and sediment transport of a tsunami similar in magnitude to the 26 December 2004 Indian Ocean tsunami over one measured and three idealized morphologies. The model is first shown to match well the observations taken at Kuala Meurisi, Sumatra, and then used to examine in detail the processes that occur during the tsunami. The model predicts that at a given cross-shore location the onshore flow accelerates rapidly to a maximum as the wavefront passes, and then gradually decelerates before reversing direction and flowing offshore. The onshore flow does not tend to zero everywhere at maximum inundation, but instead flow reversal occurs near the shoreline even as the wavefront continues to inundate landward. While some sediment is eroded by the passing wavefront, the suspension of sandy sediment is dominated by the long-duration, high-velocity backwash that occurs along the beach face and offshore of the shoreline. Some of the sediment suspended during backwash is advected shoreward by the subsequent wave, creating large spatial gradients in the suspended sediment concentrations, which may not be in equilibrium with the local hydrodynamics. The inundation and transport of sediment during a tsunami can be affected by complexities in the morphological profile and interactions between multiple waves, and many of the hydrodynamic and sediment transport processes predicted here are similar to analogous processes previously observed in the swash zone.Citation: Apotsos, A., G. Gelfenbaum, and B. Jaffe (2011), Process-based modeling of tsunami inundation and sediment transport,

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“…The characteristics of modern and Holocene tsunami deposits have been extensively reviewed (e.g., Dawson et al, 1991;Minoura and Nakaya, 1991;Hemphill-Haley, 1996;Dawson and Shi, 2000;Dominey-Howes et al, 2006;Morton et al, 2007;Shiki et al, 2008;Bourgeois, 2009;Apotsos et al, 2011;Szczuciński et al, 2012). Although some characteristics are common to many tsunami deposits, most deposit characteristics are strongly dependent on site geomorphology and sediment sources.…”

Section: Identifying Tsunami Depositsmentioning

confidence: 99%

Tsunami recurrence in the eastern Alaska-Aleutian arc: A Holocene stratigraphic record from Chirikof Island, Alaska

et al. 2015

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Despite the role of the Alaska-Aleutian megathrust as the source of some of the largest earthquakes and tsunamis, the history of its pre-twentieth century tsunamis is largely unknown west of the rupture zone of the great (magnitude, M 9.2) 1964 earthquake. Stratigraphy in core transects at two boggy lowland sites on Chirikof Island's southwest coast preserves tsunami deposits dating from the postglacial to the twentieth century. In a 500-m-long basin 13-15 m above sea level and 400 m from the sea, 4 of 10 sandy to silty beds in a 3-5-m-thick sequence of freshwater peat were probably deposited by tsunamis. The freshwater peat sequence beneath a gently sloping alluvial fan 2 km to the east, 5-15 m above sea level and 550 m from the sea, contains 20 sandy to silty beds deposited since 3.5 ka; at least 13 were probably deposited by tsunamis. Although most of the sandy beds have consistent thicknesses (over distances of 10-265 m), sharp lower contacts, good sorting, and/or upward fining typical of tsunami deposits, the beds contain abundant freshwater diatoms, very few brackish-water diatoms, and no marine diatoms. Apparently, tsunamis traveling inland over low dunes and boggy lowland entrained largely freshwater diatoms. Abundant fragmented diatoms, and lake species in some sandy beds not found in host peat, were probably transported by tsunamis to elevations of >10 m at the eastern site. Single-aliquot regeneration optically stimulated luminescence dating of the third youngest bed is consistent with its having been deposited by the tsunami recorded at Russian hunting outposts in 1788, and with the second youngest bed being deposited by a tsunami during an upper plate earthquake in 1880. We infer from stratigraphy, 14 C-dated peat deposition rates, and unpublished analyses of the island's history that the 1938 tsunami may locally have reached an elevation of >10 m. As this is the first record of Aleutian tsunamis extending throughout the Holocene, we cannot estimate source earthquake locations or magnitudes for most tsunami-deposited beds. We infer that no more than 3 of the 23 possible tsunamis beds at both sites were deposited following upper plate faulting or submarine landslides independent of megathrust earthquakes. If so, the Semidi segment of the Alaska-Aleutian megathrust near Chirikof Island probably sent high tsunamis southward every 180-270 yr for at least the past 3500 yr.

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Tsunami inundation and sediment transport in a sediment-limited embayment on American Samoa

Cited by 57 publications

References 26 publications

Numerical simulation of erosion and deposition at the Thailand Khao Lak coast during the 2004 Indian Ocean tsunami

Numerical simulation of erosion and deposition at the Thailand Khao Lak coast during the 2004 Indian Ocean tsunami

Process-based modeling of tsunami inundation and sediment transport

Tsunami recurrence in the eastern Alaska-Aleutian arc: A Holocene stratigraphic record from Chirikof Island, Alaska

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